A voluntary associa



Oct. 23, 1928.

A. E. MAYNARD GRINDSTONE Filed Dec. 4, 1926 '2 Sheets-Sheet l PatentedGet. 23, 1928.

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ALBERT E. Ivl'AYNlBD, G SOUTZ-IBRIDGE, MASSACHUSETTS, ASSIGNOB TOAMERICAN OPTICAL COMPANY, OF SGUTIIBRIDGE, MASSACHUSETTS, A VOLUNTARYASSOCIA- TION OF MASSACHUSETT'.

GRINDSTONE.

Application filed. December 4:, 1926. Serial no 152 554.

This invention relates to improvements in grindstones and has particularreference to a split or divided 'rindstone for grinding bevel edges.

5 The principal object of this invention is to provide improved meansfor separating a divided or split rindstone so that it. may be trued.

Another object of the invention is to provide simple and e'fiicientmeans for holding together in aligned position the portions of a dividedor split grindstone.

Another object of the invention is to provide simple and means fortruing a bevel grooved grindstone in which the bevelled parts of thestone may be separated.

Other objects and advantages of the invention will become apparent fromthe following description taken in connection with the accompanyingdrawings and it will be understood that many changes in the details ofconstruction and arrangement of parts may be made without departing fromthe spirit of the invention as expressed in the accornpanying claims. I,therefore, do not wish to be limited to the exact details ofconstruction and arrangements shown.

' Referrin to the accompanying drawings: Figure 1 is a front elevationof a mounted grindstone embodying the invention;

Figure 2 is a fragmentary cross sectional view on line 22 of Figure 1;

Figure 3 is a top or plan view of Figure 1 shown partially in section.

Prior to my invention bevel grooved grindstones have been made in onepiece with a bevel groove in the periphery. It has been found fromexperience that it is difficult to true such stone due to thefact thatthe truing is not correct in the bottom of the groove. It has also beenfound that such a stone is not exactly accurate in its grindingpropertiesdue to the fact that the bottom of the groove cannot beperfectly madein such a stone.

It is the object of my invention, therefore. to overcome thesedifficulties of grinding and of truing by simple and eilicientarrangements of separating the stone on the division lineat the bottom,of the groove.

Referring to the drawings wherein similar characters denotecorresponding parts throughout, a grindstone 1 made in two halves 2 and3 and having the bevelled faces 4 and 5 is mounted on a shaft 6 in thebearings 7 and 8. The grindstone is turned by the pulley 9 and'the belt10 in the usual manner. The sections2 and 3 of the grindstone 1 aremounted on a hub or carrier 11. The section 3 is directly secured to thehub 11 by means of an adhesive strip 12 while the section'2 is slidablyconnected to the hub 12 by means of the adjusting collar 13 to which itis secured by an adhesive strip 14. The adjustable collar 13 is screwthreaded at- 15 to the hub 11 and has in its periphery, openings 16 fora spanner or other wrench connection. The section 2 may be advanced byturning the collar 13 until it engages the section 3 making in effect acomplete bevel edge grindstone having the bevels 4 and 5. By reversingthe action of the screw collar 13 the parts 2 and 3 may be separated.The hub 11 is secured to the shaft 6 by means of the key 17 so that thegrindstone members 2 and 3 rotate with the shaft 6.

hen the parts of the stone 2 and 3 are separated as shown in Fig. 3 thesection 2 is locked against rotation on the collar 11 by means of theset screw 18 which is tightened up after the section 2 has been broughtto the position shown in Fig. 8. This is done so that the truing of thestone may be carried on as described hereinafter without having thesection 3 rotate on the screw thread of the hub 11.

The bevel edges 4 and 5 of the stone sections 2 and 3respectively aretrued by a diamond point 19 held in place on the truing rod 20 whichslides in the guide members 21. The guide members 21 are secured to abase plate or frame 22 which in turn slides in the slide way 23 on thebase 24 of the grindstone frame. The plate 22 is advanced towards orwithdrawn from the grindstone by means of the screw 25 having the turnnut 26. The truing rod 20 has a handle 27 by which the truing rod may heslid longitudinally in the guide 21 to advance it towards the ston orwithdraw it therefrom, the guides 21 being related to the grindstone onthe angle of the bevel faces of the stone one on each side. The truingrod 20 is retained in place in the guides 21 by means of the collar 28which is located in ting angle to the bevel face or place by the setscrew 29 and which may turned by the handle 30. The truingi ro isprevented from turnin in the gut by means of the pin 31, thepin ope thegroove in "nines 19 mounted o1 oteo of the set screw pivot 34 by wh mendpoint 19 may be so,

In the trump; operation the tr vanced by means of the scren posit-ionwith relation to the o and the truing rod 20 nnshc l in the guides 21dmina; the this pushi back and i hand. lVh l 3 of the grincst completedthe mend :oint 19 is on the opposre s' re tl rough as above o y to =3 Inthis way each s te or trued to the pronerbeve.

- shown in J understood that before is performed the two po i'tions oftl 2 and 3 are separated by the colla scribed and atter the trui beendone the two s brought up to hear one a5 shown in Fig. 1. The fromturning); by means 0" which tightens the collar The dian end or cuttingpi, "T 1 position by the screw pivot driver, the screw having; the rehead slot.

From the foregoing description it will b seen that I have proviced asimple, ctli' and economical means for producing a divided bevelgrindstone wherein the pa tsm 1; be readily separated or locked to,;ether a wherein the par s may be accura 'e y and ciliciently trued,thus insu proper reenest-i: of the groove at its bottom so that the workthat is being; bevel ed in the-g ro e will have a true apex.

Having describec the in; Cl'ltl" 1. A bevelled edge prising; a base,Sllil'i' r i the base, a grindstcne hub on the shaft, a sectional 'rin,xer the .iub having an angzged glancing ccgre, a second sectional'indstoae n ember movebly mounted on the hub and ham in an angledgrinding edge, the diameters of the adlaecnt faces of the grindstonemembers than those of the outer feces, no locking; the-second grindstonenembe' the hub in spaced relation to the first stone mem-- base hevine nU ber, guide way members on i ective angled g'rmchn edges of the grillesn, I claim:

,unted on truing tool ,e uides parallel to the l one members wherebyeach angled face of grinding ft edges oi. the grindstones may be -ruedby a truing tool in. the truing tool guide when the sections of thegrindstones are separated and both secti ns locked with respect to the Abevelled ed;

a base, a s 'HlilliGL'l on l a 1 1,,, i nub on the sectional grindstenememberon the hub aving an angled grinding edge, a second sectionalgrindstone member movably d on the he; and having an angled edge, thediameters of the adj cent storm members being" short l c ides on thebase towards and away the the grgrzndstmic sections. 9 r ,1 L; l v" 1*oer will. ed; grinding; macisnc coinine' a l; iat't rotal'c y mounted onll, base, a gri'intlstone holdL g hub on the lime, a sect onalgrindstone member m the nub and having an :mgled grinding edge, a secondsectional grinc s onemember movably :r'iounted on the hub and having aniglec. edge, the diameters of the adjacent faces ol the grindstonemembers being shortei than those of the outer faces, means for lockingthe second grindstone membe on the hub in spaced relation to the firstgrindstene i ember, guide way members on the base hav 9 truing toolgruidcs parallel o the respec- .e angled grinding edges efthe grindstoneincn'ibers, and a separable'truing tool in one of the truing toolguide-ways.

i. A bevelled edp grinding; machine comprising; a base, a shaft r:tatably moon-tee on the basc, a 'rindstone holding hub ontlie shaft, asectional grindstone member on the hub having an angled grinding edge, asecond sectional grindstone mem er movably n ounted on the hub andhaving an angled. L incline edge, the diameters of the adjacent faces 1"the grindstone members b ing short or than those oi? their enter it es,means for ie of the outer ifaecs, 1neans for lockingthe secondgrindsione member on the hub in spaced relation to the first grindstoneALBERT MAYNARD.

